Author: Cai, Y.
Paper Title Page
TUPFI016 Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy 1364
 
  • Y. Nosochkov, Y. Cai, M.-H. Wang
    SLAC, Menlo Park, California, USA
  • R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme*. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.
 
 
TUPFI017 Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy 1367
 
  • Y. Nosochkov, Y. Cai, M.-H. Wang
    SLAC, Menlo Park, California, USA
  • R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first*. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented.
* Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.
 
 
WEPWA075 High-gain X-ray FELs using a Transverse Gradient Undulator in an Ultimate Storage Ring 2286
 
  • Y.T. Ding, P. Baxevanis, Y. Cai, Z. Huang, R.D. Ruth
    SLAC, Menlo Park, California, USA
 
  An “ultimate” storage ring based on PEP tunnel has been designed to achieve diffraction limited emittance (at 1.5 Angstrom)[*]. With sufficient peak current, the beam brightness of such an “ultimate” storage ring may be sufficient to drive a short-wavelength, high-gain FEL. However, the large energy spread intrinsic to storage rings hinders the FEL applications for x-ray wavelengths. To overcome this problem, we adopt the transverse-gradient undulator concept[**][***] to study a high-gain FEL in an ultimate storage ring. Using PEP-X as an example, we showed from simulations that a high-gain FEL at the photon energy 1keV with a peak power of a few hundred megawatts can be achieved within a saturation length of 100 meters.
* Y. Cai et al., Phys. Rev. ST Accel. Beams 15, 054002 (2012).
** T. Smith et al., J. Appl. Phys. 50, 4580 (1979)
*** Z. Huang, Y. Ding and C. B. Schroeder, Phys. Rev. Lett 109, 204801 (2012).